Valve mechanism for rock drills



` rock drill having Patented Aug.l i3, 1929.

UNITED STATES PATENT OFFICE.

WILLIAM A. SMITH, JR., 0F PHILLIPSBURG, NEW JERSEY, ASSIGNOR T0INGERSOLL- RAND COMPANY, OF JERSEY CITY, NEW JERSEY, A CORPORATION 0FNEW JER- SEY.

VALVE MECHANISM FOR ROCK DRILLS.

Application filed November 22, 1928.

This invention relates to rock drills, but more particularly to thevalve mechanism intended for use in effecting the distribution oipressure iiuid to the cylinder oi' rock drills oi the fluid actuatedtype.

The objects of the invention are to obtain a rapid action of the valveand to impart stability to the valve in its limiting positions, thuspreventing leakage of pressure fluid into the piston chamber in advanceof the piston and a resulting loss in force of the blow of the hammerpiston against the working implement which it is intended to actuate.

Other objects will be in part obvious and part pointed out hereinafter.Inthe drawings illustrating a practical application of the invention andin which similar reference characters refer to similar parts,

Figure l is a vertical sectional elevation of a portion of the rockdrill equipped with a valve mechanism constructed in accordance with thepractice of the invention,

Figure 2 is a transverse view talren through Figure l on the line 2 2looking in the direction indicated by the arrows, and

Figure 3 is a` perspective view of the valve and the parts comprisingthe valve chest.

Referring to the drawings, A designates a a cylinder B in which isformed a piston chamber C to accommodate a reciprocatory hammer pistonD. The cylinder B has in this instance a free exhaust ort E which iscontrolled by the piston D.

isposed at the forward end of the cylinder B is a front cylinder washerF which forms a closure for the front end of the piston chamber C andhas a bore G to slidably receive the nose or extension H of the piston DIn the rearward end of the cylinder B is an enlarged boie J and in theinnermost end of said bore J is a back cylinder washer K which forms aclosure for the rearward end of the piston chamber C.

The bore J may be of a suitable depth to receive, among other elements,rotation mechanism comprising in this instance a. rotation ratchet Lwhich may be secured in operative position in any suitable manner. Therotation ratchet L has the usual intro- Serial No. 321,132.

verted teeth O adapted for engagement with spring pressed pawls Pcarried by the head of a rifle bar R for imparting rotary movement tothe piston D and thus also to the working implement which the piston isintended to actuate, the rifle bar R being of course interlockedslidably with the piston D in the usual manner.

In the construction illustrated, the rot-ation ratchet L serves as aseat for a back head S disposed at the extreme rearward end of thepiston A and secured to the cylinder in an convenient manner, as forinstance, by t e usual side rods (not shown).

The back head S is provided with a throttle valve chamber T for thereception of a throttle valve U whereby the admission or' pressure fluidfrom a source of supply into the drill may be controlled. The throttlevalve U as illustrated is of the rotary type and has a central chamber Vwhich may be in constant communication with a source of pressure Huidsupply. In the side wall of the throttle valve is a port W which, in theopen position of the throttle valve, registers with a passage X leadingto a supply reservoir Y in the forward or inner end of the back head A.Y

Interposed between the back cylinder washer K and the rotation ratchet Lis a Valve mechanism designated generally by Z for effecting thedistribution of pressure fluid to the ends of the piston chamber C toactuate the piston. The valve mechanism in this instance comprises avalve chest b which serves as a seat for the rotation ratchet L and thehead Q, of the rile bar and is in turn seated on a valve seat c disposedon the back cylinder washer K.

In the valve chest b is a. valve chamber l from the forward side ofwhich leads a rearward inlet passage e to the rearward end of the pistonchamber C. From the same side of the valve chamber l leads a frontinletpassage f, that is, both the inlet passages e and f extend throughthe valve seat c and through the back cylinder washer K, and the inletpassage f is continued through the cylinder B to a point near the frontend of the piston chamber C into which it opens.

The pressure fluid for actuating the piston D is conveyed to the valvechamber d through a plurality of supply passages g' which lead from thesupply reservoir Y through the valve seat c where they open intocavities 7i in the forward surface of the valve seat so that the backcylinder washer l forms a closure for one side of said cavities. rlChepressure fluid admitted'into the cavities 7L. flows therefrom throughports j in the valve seat and which ports all'ord communication betweenthe cavities i and the valve chamber (Z. rllhe ports in this instanceopen into the valve chamber Z at points adjacent the inlet passages eand and therefore lie directly beneath a distributing valve k disposedin the valve chamber (l for controlling the distribution of pressurefluid to the piston chamber C. l

rllie distributing` valve 7c is illustrated as being of the oscillatoryplate type having an intermediate fulcruin 0 upon which the valve isadapted to rock from one limiting position to the other, and hasoppositely extending wings Q9 and g which in this instance overlie boththe supply ports and the inlet passages e and lf desired the valvechamber ci may be provided at its rearward side and at opposite endswith suitable recesses r into which pressure fluid may flow to actagainst the rearward surfaces of the wings p and g to assist in holdingthe seated ends or wings of the valve firmly over the inlet passageswhich they control.

From the foregoing description, it will be readily apparent to thoseskilled in the art that the valve 7c will be exposed to a positivepressure, that is, to full line pressure for actuating it from onelimiting position to the other. The valve is in no wise dependent uponany suction action of' the pressure fluid during its passage into thepiston chamber for its movement. ln fact the pressure fluid does notpass over any portion of the valve during its course from the supplypassages to the inlet passages such its edges, as is customary in valvesof this type, but flows across only the forward surfaces of the wings pand g.

rl`he operation of the device is as follows: 1With the throttle valve Uin the open position, pressure fluid will flow through the port W andthe passage X into he supply reservoir Y. From thence it flows throughthe supply passages g into the cavities fr and through the supply portsto act against the wu l 1i and Y7.

vWith the piston occupying the rearwardmost position in the pistonchamber C, the forward portion of the piston chamber will be open toatmosphere through the exhaust port E, therefore the pressure fluidacting against the wings g will raise said wing and pressure fluid willthen flow from 'the supply ports j into the valve chamber d, across theforward surface of the wing Q through the inlet passage e and into therearward end of the piston chamber C to impel the piston D forwardly.

It will thus be noted that the pressure fluid during its course throughthe valve chamber al exerts a positive pressure against the forwardsurface of the wing g for holding said wing in the raised position.Pressure fluid will, of course, act against a portion of the rearwardsurface of the wing g.

Due to the differential in area of the exposed surfaces of the wing g,however, the pressure fluid acting against the forward surface willpredominate and the valve will therefore remain firmly in the raisedposition until the piston D uncovers the free exhaust port E. lVhen thepiston D reaches this point in its travel, there will be an abrupt dropin pressure fluid in the rearward end of the piston chamber C and thevalve ic will be immediately tilted to its other limiting position, bothby the compression created in the front end of the piston chamber C andby the pressure fluid act-ing against the forward surface of the wing p.

The reversal of the valve in the manner described may take place at orslightly prior to the instant at which the piston D delivers its blowagainst the working implement. Pressure fluid will then flow from thevalve chamber through the inlet passage f into the front end of thepiston chamber C to return the piston D to its initial position. Duringthe rearward travel of the piston, compression will of course be createdin the rearward end of the piston chamber C and such compression willact through the inlet passage e against the forward surface of the wingg to assist the live pressure fluid in the supply ports y' which actsagainst the forward surface of the wing g for again tilting the valve kto its other limit-ing position.

I claim:

1. In a fluid actuated rock drill, the combination of a cylinder and apiston, an exhaust port for the cylinder, a valve chest having a valvechamber, inlet passages leading from one side of the valve chamber tothe ends of the cylinder, an oscillatory plate valve in the valvechamber controlling the inlet passages, said valve having oppositelyextending wings and an intermediate fulcrum whereon said valve isadapted to rock, and supply passages opening into the same side of thevalvechamber as the inlet passages to expose the valve to pressure fluidfor actuating said valve from one limiting position to another.

2. ln a fluid actuated rock drill, the combination of a cylinder and apiston, an exhaust port for the cylinder, a valve chest having a valvechamber, inlet passages lead- Ying from one side of the valve chamber tothe ends of valve in the cylinder, an oscillatory plate the valvechamber controlling the inlet passages, said valve having oppositelyextending wings and an intermediate fulcrum whereon said valve isadapted to rock, and supply passages opening into the same side of thevalve chamber as the inlet passages to constantly expose thecorresponding sides of the wings to pressure fluid under full linepressure for actuating said valve from one limiting position to another.

3. In a fluid actuated rock drill, the combination of a cylinder and apiston, an exhaust port for the cylinder, a valve chest having a valvechamber, inlet passages leading from the forward side of the valvechamber to the ends of the cylinder, an oscillatory plate valve in thevalve chamber controlling the inlet passages, said valve having a pairof oppositely extending wings and an intermediate fulcrum whereon saidvalve is adapted to rock, and supply passages opening into the forwardside of the valve chamber to constantly expose the forward surfaces ofboth Wings to pressure fluid for actuating the valve from one limitingposition to another.

4. In a fluid actuated rock drill, the combination of a cylinder and apiston, an exhaust port for the cylinder controlled by the piston, avalve chest having a valve chamber, inlet passages leading from thevalve chamber to the cylinder, an oscillatory plate valve in the valvechamber having an intermediate fulcrum Whereon said valve is adapted torock and a pair of oppositely extending wings to control the inletpassages, and supply passages conveying pressure fluid into the valvechamber to expose corresponding surfaces of both wings to pressure fluidfor actuating the valve and for supplying pressure fluid across one sideof the valve to the inlet passages.

In testimony whereof I have signed this specification.

WILLIAM A. SMITH, JB.

